As a Radec player, and my secondary Nathan Drake, I love to get a good distance away from people. A good range is perfect for slowly building up your AP. But, what makes me the most aggravated is combos. Kratos, Raiden, and to a lesser extent Dante have these characteristics. And they get a lot of hate. Kratos is good at everything, but Raidens only real advantage are his amazing combos. He has no range, his supers suck, no projectiles, and is a big target for level 1 and 2 supers. He also has greast speed, but if Im far enough away I won't be worried about that. So, what do you think is the biggest thing to consider when making a character OP or UP? Mine is combos for OP, and speed for UP
-Are you safe on block?
-Can you kill reliably and easily?
-Do you have a good approach?
-Failing that, can you successfully zone?
-Do you have practical combo starters? A few or a lot?
-Can you safely poke an opponent with no fear of retaliation?
-Do you have a good grab and can you combo off of it?
-Do you have disjoincted hitboxes?
-Do you have anything that reduces or removes your hurtbox?
-Do you have good movement options? Do you have an escape?
-Are there any characters that can completely shut you down?
These are just some basic categories competitive players like myself look for in a character. A lot of this stuff can even be deduced just from just watching gameplay footage (Which is why a lot of people think the Flash will be ridiculous in Injustice. There's been talk of Green Lantern and Aquaman being really good too. I personally think Sinestro and Ares will also be beastly.).
All in all though, being able to stay safe is one of the most important factors.